/**
 * Copyright 2013-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule SyntheticUIEvent
 */

'use strict'

var SyntheticEvent = require('./SyntheticEvent')

var getEventTarget = require('./getEventTarget')

/**
 * @interface UIEvent
 * @see http://www.w3.org/TR/DOM-Level-3-Events/
 */
var UIEventInterface = {
  view: function (event) {
    if (event.view) {
      return event.view
    }

    var target = getEventTarget(event)
    if (target != null && target.window === target) {
      // target is a window object
      return target
    }

    var doc = target.ownerDocument
    // TODO: Figure out why `ownerDocument` is sometimes undefined in IE8.
    if (doc) {
      return doc.defaultView || doc.parentWindow
    } else {
      return window
    }
  },
  detail: function (event) {
    return event.detail || 0
  }
}

/**
 * @param {object} dispatchConfig Configuration used to dispatch this event.
 * @param {string} dispatchMarker Marker identifying the event target.
 * @param {object} nativeEvent Native browser event.
 * @extends {SyntheticEvent}
 */
function SyntheticUIEvent(
  dispatchConfig,
  dispatchMarker,
  nativeEvent,
  nativeEventTarget
) {
  return SyntheticEvent.call(
    this,
    dispatchConfig,
    dispatchMarker,
    nativeEvent,
    nativeEventTarget
  )
}

SyntheticEvent.augmentClass(SyntheticUIEvent, UIEventInterface)

module.exports = SyntheticUIEvent
